#include <bits/stdc++.h>
using namespace std;

int ask(int l, int r) {
    if (l >= r) return -1;
    cout << "? " << l + 1 << ' ' << r + 1 << endl;
    int ans;
    cin >> ans;
    return ans - 1;
}

int main() {
    int n;
    cin >> n;
    int l = 0, r = n;
    while (r - l > 1) {
        int m = (l + r) / 2;
        int smax = ask(l, r - 1);
        if (smax < m) {
            if (ask(l, m - 1) == smax) {
                r = m;
            } else {
                l = m;
            }
        } else {
            if (ask(m, r - 1) == smax) {
                l = m;
            } else {
                r = m;
            }
        }
    }
    cout << "! " << r << endl;
    return 0;
}
